Background: Restaurant workers may be exposed to fungal bioaerosols that can colonize the upper respiratory tract and pose potential occupational and public health risks. Opportunistic fungi, particularly non-albicans Candida, are clinically important because of their virulence traits and possible antifungal resistance. This study aimed to identify nasal fungal isolates from restaurant workers and assess selected phenotypic and molecular virulence markers.
Methods: Ninety-three nasal swabs were collected from restaurant workers in Kirkuk, Iraq, between December 2024 and July 2025. Yeasts were identified using Sabouraud dextrose agar, Candida chromogenic agar, and microscopic examination. Molds were identified according to macroscopic and microscopic characteristics. Phospholipase activity was evaluated phenotypically using egg yolk agar. Molecular identification was performed by PCR targeting the ITS region for yeasts and the β-tubulin gene for molds, while the PLB1 gene was amplified as a virulence marker in Candida isolates.
Results: Fungal growth was detected in 30 samples (32.26%). A total of 32 fungal isolates were recovered, with Candida krusei being the most frequent species (20/32; 62.50%), followed by Candida glabrata (7/32; 21.88%). Other isolates included Penicillium chrysogenum (6.25%), Candida parapsilosis, Penicillium oxalicum, and Aspergillus niger (3.13% each). The highest culture positivity was observed among workers aged 31–40 years, but age was not significantly associated with fungal positivity. Phospholipase activity was generally low. The PLB1 gene was detected in 75% of Candida isolates, most commonly in C. krusei.
Conclusion: Nasal fungal colonization was detected in nearly one-third of restaurant workers, predominantly by non-albicans Candida. Molecular methods improved species-level identification and showed frequent PLB1 detection despite low phenotypic phospholipase activity.